This invention is directed to the formation of one or more channels into the wall of a patient's heart. Such channels may be used to increase blood flow to heart tissue, for the delivery of therapeutic or diagnostic agents to various locations in the patient's heart or for a variety of other utilities.
The formation of a channel in a patient's ventricular wall is called trans myocardial revascularization. The first clinical trials of the trans myocardial revascularization procedure were performed by Mirhoseini et al. See for example the discussions in Lasers in General Surgery (Williams & Wilkins; 1989), pp 216-223. Other early disclosures of this procedure are found in an article by Okada et al. in Kobe J. Med. Sci 32, 151-161, October 1986 and in U.S. Pat. No. 4,658,817 (Hardy). These early references describe intraoperative revascularization procedures which require an opening in the chest wall and include formation of the channels through the epicardium.
Copending application Ser. No. 08/361,787, filed Dec. 20, 1994 (Aita et al.), which is incorporated herein in its entirety, describes a system for trans myocardial revascularization which is introduced through the chest wall. In U.S. Pat. No. 5,389,096 (Aita et al.) a percutaneous method is described for forming a channel in a patient's ventricular wall wherein an optical fiber device is advanced through a peripheral artery such as the femoral artery and through the aorta into the patient's left ventricle. Within the left ventricle, the distal end of the optical fiber device is directed toward a desired location on the patient's endocardium and urged against the endocardial surface while a laser beam is emitted from its distal end to form the channel. The depth of penetration of the distal end of the laser device is affected by the force applied by the distal end to the tissue into which the channel is being formed. Because of the nature of the environment, i.e. fluid currents within the heart chamber, the moving interior heart surface and the uneven surface of the patient's endocardium, controlling the force applied to the endocardial tissue by the end of the laser device can be quite difficult. Complete penetration through the ventricular wall from within the ventricular chamber is not desirable.
A system for limiting the penetration of laser type devices is described in co-pending application Ser. No. 08/584,957, filed on Jun. 7, 1995, which is hereby incorporated into this application by reference. However, with the device described in the above copending application, it was found difficult to insert the probe tip of the device into the adapter on the proximal end of the guiding catheter which is used to deliver the laser device into the interior of the patients heart chamber. The present invention minimizes the difficulties with this prior channel forming devices as well as other such devices.